The problem of dispensing fluid doses of a selected volume is met in many fields, particularly in the pharmaceutical field. Apparatus for charging a large number of petri dishes automatically with agar is disclosed in the above-identified application. While a number of devices are already available, the accuracy and precision of such devices when compared with the cost of same are not as great as could be desired. One difficulty is that the delivery system may not have been properly calibrated initially. Another difficulty arises from the fact that the volume of liquid delivered per stroke or per revolution may change with time. This is particularly the case where pumps which are based on compression of rubber tubing are concerned. The internal diameter of the rubber tubing varies from lot to lot, and the flexibility of the rubber decreases with age. Accordingly, it would be desirable that a device be provided which makes it possible to calibrate the pump easily and as often as desired. Further, in view of the fact that fluid dispensers are frequently called upon to dispense repetitively a large number of doses, it would be desirable that the device be capable of dispensing a selected number of doses, each of a selected size, automatically. In addition, the device should be capable of introducing a hiatus between successive doses to provide for moving fresh containers into place at the delivery point. The present invention is designed to provide these capabilities.